Grinding wheel mandrel



Feb. 18, 1936. J. H. BLAIR GRINDING WHEEL MANDREL Filed March 2l, 1953 INVENTOR: Jamesjfla' AT ORNEY Ik... u1)

Patented Feb. 18, 1936 UNITED STATES PATENT FEE GRINDING WHEEL MANDREL Application March 21, 1933, Serial No. 661,895

5 Claims.

This invention relates to improvements in dental tools and more particularly to improvements in grinding wheel mandrels and similar devices.

In the dental art use is made of rotating abra- 5 sive wheels for many purposes. Ordinarily a wheel of this character is secured to the end of la rotatable mandrel by means of a bolt threaded into the mandrel, the wheel being held between the head of the mandrel and the head of the bolt.

1,) In order to insure that the wheel will rotate with the mandrel it is necessary to tighten the bolt to such an extent that the wheel is firmly held by the head of the bolt. Such tightening is usually accomplished by the use of a screw driver or other 1,-, suitable tool.

An object of the invention is to provide an improved grinding wheel mandrel assembly of such character that the abrasive wheel is locked for rotation with the mandrel at all times.

Another object of the invention is to provide a grinding wheel mandrel assembly of such character that the locking member will be tightened automatically when the wheel is put in use.

A further object of the invention is to provide in conjunction with a rotatable mandrel and its bolt a sliding sleeve resiliently. pressed toward the head of the bolt.

The construction of the present invention consists of a rotatable mandrel having a recess in one end thereof and a further recess which is internally threaded. Slidably secured to the recessed end of the mandrel is a sleeve which is pressed outwardly normally by means of a spring positioned in the first recess in the end of the mandrel. A bolt passes through the head of the sleeve into threaded engagement with the threaded recess of the mandrel. An abrasive disk of any suitable character can be positioned between the head of l the sleeve and the head of the bolt. When the to disk is so positioned with the bolt passing therethrough it is locked in position by manually threading the bolt into the mandrel until the disk is held between the end of the sleeve and the head of the bolt. Since this sleeve is pressed outwardly by the spring, the disk will be held against any rotation independently of the sleeve and the bolt. As a result of this gripping, if the mandrel is rotated in such direction as to normally tighten the bolt, it will be observed that such rotation of necessity causes the disk to be gripped under increasing pressure as the rotation continues.

Other features and advantages of the invention will be apparent by reference to the following detail description taken in conjunction with the acerally a grinding wheel mandrel which has an enlargement I I at one end thereof. This end of the mandrel is hollowed out to form a recess I2 and is further hollowed out to form a threaded recess Secured to this end of the mandrelis a sleeve member I5 provided with a central aperture I6 in the end thereof and having the material of the open end thereof spun inwardly as at I'I to prevent withdrawal of the sleeve from the mandrel. This inwardly spun portion I'I, under certain conditions, engages the shoulder I8 formed by the enlargement II. A spring I9 is positioned in the recess I2 in such fashion as to normally press the sleeve outwardly until the part Il engages the shoulder I8.

A threaded bolt 20 having a large head 2| passes through the opening I6 in the sleeve into threaded engagement with the threads oi the recess I4.

In connection with this assembly, use may be made of an abrasive disk 22 of any suitable char- S51 acter. The -abrasive material may be emery, carborundum, or any other ldesired substance.

The operation and use of this device is substantially as follows: When it is desired to secure a disk 22 to the end of the mandrel as ji.-

sembly, the bolt 2li is removed entirely from the assembly and inserted through an opening 24 in the middle of the disk. The bolt is then inserted through the opening I6 and threaded into the opening I4. Of course, when the bolt has been i removed from the assembly, the spring I9 forces the sleeve I5 outwardly to the full extent permitted by the construction of the device. The disk is then locked in place by further `threading the bolt into the recess I4. This further movement can be accomplished by merely manually turning the head 2l. As a result of such turning, the disk becomes gripped between the head 2I and the end sleeve I5. turning of the bolt is resisted by the strength of the spring I9, the mandrel can be rotated by any suitable source of power. The direction of rotation of the mandrel as indicated by arrows in the drawing is such as would normally tend When further to cause further threading of the bolt into the threaded recess.

Since the disk is firmly gripped between the head of the bolt and the sleeve, it follows that the disk will be positively rotated whether the bolt be tightened to the greatest possible extent or not. In other words, if the mandrel is put in use with the disk member as described, contact between the disk and an object to be ground will result in further tightening of the bolt. By this arrangement, it will be seen that the necessity for tightening the bolt by means of a screw driver or other tool is entirely elimihated, thereby considerably reducing the time necessary for assembling the parts of the mechanism and also reducing wear on the head of the bolt.

From the foregoing, itwill be seen that the present invention provides an arrangement in which an abrasive disk can be held for positive rotation regardless of whether the locking bolt is tightened to the greatest possible extent or not. The assembly also provides a tool in which tightening of the bolt and locking the disk to the mandrel is accomplished automatically upon rotation of the mandrel and use of the disk.

It will be understood that the present invention is capable of embodiments other than that shown in the present drawing. Therefore, the invention is not to be limited by the illustrated embodiment but is to be limited only by the scope of the following claims.

I claim:

1. Apparatus of the character described, comprising a rotatable rod-like member having a threaded opening in one end thereof, a cupshaped sleeve slidably secured to the same end of said member with the inturned bottom of the sleeve covering the end of the member, said bottom having an opening therein substantially coaxial with said threaded opening, resilient means forcing said sleeve outwardly, and a bolt passing through said sleeve into threaded engagement with said opening to hold a disk between the end of said sleeve and the head of said bolt, said sleeve being movable to contact the inturned bottom thereof directly with the end of the rod-like member.

2. Apparatus of the character described, comprising a rotatable rod-like member having a threaded opening in one end thereof, a cupshaped sleeve slidably and rotatably secured to the same end of said member with the inturned bottom of the sleeve covering the end of the member, said bottom having an opening therein substantially coaxial with said threaded opening, resilient means forcing said sleeve outwardly, and a bolt passing through said sleeve into threaded engagement with said opening to hold a disk between the end of said sleeve and the head of said bolt, said sleeve being movable to' contact the inturned bottom thereof directly with the end of the rod-like member.

3. Apparatus of the character described, comprising a rotatable rod-like member having a y recess in one end thereof and a threaded recess extending from said first recess, a cup-shaped sleeve slidably secured to the same end of said member with the inturned bottom of the sleeve covering the end of the member, said bottom having an opening therein substantially coaxial with said threaded opening, resilient means seated in said rst recess forcing said sleeve outwardly, and a bolt passing through said sleeve into threaded engagement with said second recess to hold adisk between the end of the sleeve and the head of the bolt, said sleeve being movable to contact the inturned bottom thereof directly with the end of the rod-like member.

4. Apparatus of the character described, comprising a rotatable rod-like member having a recess in one end thereof and a threaded recess extending from said first recess, a cupshaped sleeve slidably and rotatably secured to the same end of said member with the inturned bottom of the sleeve covering the end of the member, said bottom having an opening therein substantially coaxial with said threaded opening, resilient means seated in said first recess forcing said sleeve outwardly, and a bolt passing through said sleeve into threaded engagement with said second recess to hold a disk between the end of the sleeve and the head of the bolt, said sleeve being movable to contact the inturned bottom thereof directly with the end of the rodlike member.

5. Apparatus of the character described, comprising a rod-like member having an enlargement at one end and being provided with a recess in Said enlarged end and with a threaded recess extending from said first recess, a cupshaped sleeve slidably and rotatably secured around said enlargement with the inturned bottom of the sleeve covering the end o f the member, said bottom having an opening therein substantially coaxial with said threaded opening, said sleeve being movable to contact the inturned bottom thereof directly with the end of the rodlike member.

JAMES H. BLAIR. 

